Now that we have covered the anatomy of a neuron and action potential, our next lesson in the fascinating world of biopsychology is neurotransmitters. Human life would be wildly different, if not impossible, without these essential cerebral chemicals. This article will provide an overview of the major neurotransmitters.
So what exactly are neurotransmitters? According to Neuroscientifically Challenged, a neurotransmitter is a chemical substance released by a neuron which is used to communicate with another neuron (1). As I have alluded to before, the neurotransmitter is the currency for the electrochemical exchange of neurological economy. A more in-depth definition of neurotransmitters is chemical signals released from presynaptic nerve terminals into the synaptic cleft (2). There is a multitude of neurotransmitters that have numerous effects on the human psyche, but today we will focus on the ones that are the most impactful to the human psyche: dopamine, serotonin, norepinephrine, acetylcholine, GABA, and glutamate.
Before we can delve into this very exciting world of neurotransmitters, we must understand two very salient pieces of information about neurotransmitters. There are excitatory neurotransmitters, like glutamate, which trigger the postsynaptic neuron to fire, and inhibitory neurotransmitters, like GABA (gamma-aminobutyric acid), which stunt the postsynaptic neuron from firing.
The neurotransmitter that gains the most renown from popular culture is dopamine. Ah, dopamine, the neurotransmitter that is supposedly found in abundance in the mind of hedonists. Dr. Robert Sapolsky tells us that dopamine is less about pleasure than it is about the anticipation of a reward. A person’s dopamine levels spike not when receiving a reward, but when a chance of reinforcement, a “maybe” is introduced into the equation. Dopamine is also pertinent in attention, emotion, movement, and learning.
Serotonin is an infamous neurotransmitter for those familiar with major depressive disorder (MDD). In MDD, there is believed to be a deficiency in serotonin. Serotonin generally regulates mood, hunger, sleep, arousal levels, and sexual behavior. Closely tied to serotonin is norepinephrine, a neurotransmitter that is implicated in controlling alertness and arousal.
Sending a Snapchat message to your friends about avocado toast? You can thank your neurochemical friend, acetylcholine (Ach) for that. Acetylcholine mainly functions in movement, and it is discovered in amplitudes in efferent neurons that carry signals from sensory receptors to the brain and spinal cord. Ach is also the pivotal neurotransmitter for learning and memory.
Hopefully, if you’re living in the United States and you’re under the age of 21, you have never digested alcohol besides in a religious context. If you have, I won’t tell. If you have, you have encountered GABA, the primary inhibitory neurotransmitter. Because GABA is the main inhibitory neurotransmitter, it can decrease the likelihood that action potentials will occur, and thus decreases neuronal signaling (3). With alcohol and other depressants, GABA depresses the nervous system, slows down the brain, and disrupts memory formation.
To close off our cursory tour into the realm of neurotransmitters, we will end with my favorite neurotransmitter and the subject of my next article: Glutamate. When it comes to neurotransmitters, glutamate is the underdog and is very underrated compared to dopamine, even though it is one of the most common neurotransmitters. Without glutamate excitatory nature, learning would not be neurologically possible. As aforementioned, glutamate is the principal excitatory neurotransmitter. It is rightly associated with learning and memory. Unlike the other neurotransmitters, glutamate has a unique non-linear threshold, which is why cramming seven hours for an exam yields lower percentages of information retained and learned.
We now have a foundational comprehension of neuroanatomy, action potential, and neurotransmitters. In my next article, I will shed some light on the dark horse of the neurotransmitters, glutamate, and why this little chemical is so crucial to education and life overall.
References and Footnotes